* doc: update expired Slack invite link
* feat: add cloud mode to skill installer for team memory sharing
Adds support for Hindsight Cloud in the skill installer, enabling teams
to share memories about a codebase. Changes include:
- Add `--mode cloud` option to get-skill installer
- Install hindsight CLI binary for cloud mode (via get-cli)
- Configure ~/.hindsight/config with API URL and key
- Generate cloud-specific SKILL.md with team-aware guidance
- Distinguish between project conventions and individual preferences
- Update skills.md documentation with cloud setup instructions
Cloud mode workflow:
1. Team admin creates a bank in Hindsight Cloud
2. Each developer runs: curl ... | bash -s -- --mode cloud
3. All team members share the same memory bank
4. Knowledge retained by one member benefits everyone
